This invention relates to seats, in particular vehicle seats, having a backrest which includes a movable lumbar support.
It is known for example from United Kingdom Patent Specification No. 1,011,726 to provide a seat having a back rest which includes a back rest frame and a lumbar support member mounted on said frame by means of a support mechanism, said lumbar support member having a support surface which is arcuate about a horizontal axis transverse to the back rest, the support mechanism being operable in one mode to displace the lumbar support in a forward or rearward direction and in a second mode to raise or lower the level at which the lumbar support member engages the back of a seat occupant.
The mechanism of the above-mentioned patent is operable by a knob disposed to the rear of the back rest and involves a simple forward and backward or vertical displacement of a spring on which a lumbar support member is mounted. In this mechanism, the lumbar support member is slidable on the inner face of the backrest upholstery, and the supporting spring is slidable in a vertical guide in the back rest frame.
A requirement exists for an improved support mechanism for a lumbar support member and preferably one which is readily operable by a person while sitting on the seat, and which mechanism consequently must be easily accessible and have low frictional resistance in its operation.